1. Field of the Invention
This invention relates to a cleaning device for removing developer remaining on an image bearing member, and more particularly to a cleaning device which can carry out good cleaning without scattering the removed developer.
2. Description of the Prior Art
Heretofore, in an image formation apparatus based on electrophotography, the surface of an image bearing member has been cleaned for repetitive utilization. In such an image formation apparatus, for example, a photosensitive medium having a photoconductive layer is used as the image bearing member, and an electrostatic latent image is formed on the photosensitive medium by charging means, exposure means, etc., whereafter the electrostatic image is developed into a visible image by developing means. The visible image is transferred to a transfer medium, whereafter the transfer medium is separated from the surface of the photosensitive medium and the image thereon is fixed by fixing means, thus completing the image formation. On the other hand, the surface of the photosensitive medium after the image transfer is cleaned by a cleaning device to remove developer remaining on the surface of the photosensitive medium, thus becoming ready for reuse.
Various cleaning devices usable with such image formation apparatus have been proposed such as those based on the fur brush cleaning system, the web cleaning system and the elastic blade cleaning system. Particularly, the cleaning device based on the elastic blade cleaning system has been widely used for its simple construction, its high cleaning efficiency and its excellent durability. As compared with the fur brush and the web cleaning system, the elastic blade cleaning system suffers less from the possibility of foreign materials being admixed with the removed developer and this leads to the reusability of the developer which is a feature of the elastic blade cleaning system.
In such elastic blade cleaning system, the removed developer has a remarkable tendency to accumulate in the vicinity of the end of the elastic blade which bears against the surface of the image bearing member, and particularly in the vicinity of the top of the drum-shaped image bearing member. In order to remove such accumulated developer, it has been the common practice to provide conveyor means for the accumulated developer. Also, in the side portion or the lower portion of the drum-shaped image bearing member, a construction has been chosen in which the developer may drop by gravity. However, again in such arrangement, if the image bearing member is moved at a high speed, the tendency of the developer to accumulate on the portion of the elastic blade which bears against the surface of the image bearing member has been unavoidable.
Such accumulated developer might sometimes be fused to the surface of the image bearing member due to the friction between said developer and said surface while, on the other hand, the developer itself might be over-charged or melted to suffer from changes in its property.
Such a phenomenon as the fusion of the developer to the surface of the image bearing member or the changes in property of the developer has also occurred in the case of the fur brush cleaning system even when the image bearing member is being moved at a low speed and as compared with this, the possibility of occurrence of such phenomenon is low in the case of the elastic blade cleaning system even when the image bearing member is being moved at a high speed, but it is apparent that this is not preferable in high-speed image reproduction.
The present invention has been made in view of the above-noted situation.